Halogenated trifluoromethylstyrene materials and method of making same



to provide a method of making such new mono- Patented Jan. 1, 1952 V I UNITED STATES PATENT OFFICE HAIDGENATED TBIFLUOROMETHYLSTY- RENE MATERIALS AND METHOD 'OF MAKING SAME Gustave B. Bachman, West Lafayette, Ind., and

Leonda L. Lewis, Sanborn, N. Y., assignors to' The Purdue Research Foundation, West Lafayette, 11111., a corporation of Indiana No Drawing. Application December 26, 1947. Serial No. 794,089

\ 3 Claims. (Cl. 260-651) l 2 This invention relates to polymerizable arylmay be homopolymerized or copolymerized with vinyl compounds and alpha-alkyl arylvinyl comother oleflnic monomers, (monomers having pounds containing a trifiuoromethyl group and an olefinic group activated for vinyl type of coa halogen group directly substituted on the aropolymerization) to produce rubbers and resinous matic ring. It also relates to the method of 5 materials having especially desirable properties. preparing these materials and to polymers and In the above general formula A is selected copolymers resulting from the polymerization or from hydrogen and methyl, B is selected from copolymerlzation thereof. hydrogen, halogen and trifluoromethyl, X" is Polymerizable nuclearly halogenated arlvinyl halogen, including F, Cl and Br, and n and compounds, such as dichlorostyrene and param are integers selected from 1 and 2. The chlorostyrene, fiuorostyrene and the like, have compounds are further characterized in that heretofore been recognized to form polymers and B is hydrogen in all cases where A is methyl. copolymers having desirable characteristics for We have been unable to polymerize or copolycertain industrial applications. The nuclearly merize by the emulsion or mass technique genchlorinated styrenes are said to have exceptional 5 erally used for vinyl type polymerization and optical properties. Certain trifluoromethylstywith peroxide or free radical catalysts comrenes have also been proposed. Such compounds pounds in which A" is methyl and either or are described in the Renoll Patent 2,414,330 of both Bs are halogen, trifluoromethyl, methyl, January 14, 1947, which discloses that they polyetc. In fact we have have been unable to polymerize and copolymerize to form resinous mate- 2n merize or cop ymerize by the usual meth ds f ria.s which have a high degree of theimostability. vinyl polymerization any compounds in which It is an ob ect of the present invention to pro- A is methyl and 8" is simultaneously other vide nuclear-substituted arylvinyl compounds than hydrogen. having the advantages of both the nuclearly ha- Thus, we have been unable to polymerize or logenated arylvinyl compounds and the trifluorocopolymerize by the usual vinyl polymerization procedures a pha-methyl-ortho-fluoro-para-trifiuoromethylstyrene or any other compound to provide monomeric materials which may be having both the alpha-methyl substituent and a copolymerized with other monomeric materials substituent such as halogen. alky trifluoloto give resins and rubbery polymers having imso thyl n th a d/ r -p sit When. proved properties. however, the A" in the above general formula It is a further object of the present invention s e yl and is y og we have found that very desirable copolymers with many monomeric materials. mers may be prepared by the usual methods of Some of these as well as other objects which vinyl copolymerization involving free radical will be apparent from the following description propagation and molecular growth. When, howof the inventions are accomplished by preparever, A" is hydrogen, we have found that deing arylvinyl compounds having at least one trlsirabie homopolymers as well as copolymers may iluoromethyl group and at least one halogen be prepared, even through B is methyl, trigroup directly substituted on the aromatic ring. fluoromethyl or halogen. I While most of the arylvinyl compounds hav- Compounds within the above general formula in one or more halog ups and one or having not more than two halogen atoms and more trifllwrom yl r ps simultaneously not more than two triiluoromethyl groups usu- Subsfltllted 011 the aromatic ring y be p ally yield upon polymerization or copolymerizaduc We have been unable to polymerize tion rubbery and resinous materials that are sucopolymerize any Of these compounds unless hyperjor in some respects to those having more drogen is directly connected either to the alpha halogen, carbon of the side chain or to both of the ortho Examples of t compounds within the above end carbon atoms of the nucleus general formula found to copolymerize or homoe a o d that c p s ha the polymerize and form rubbery and resinous mageneral formula terials for commercial application are:

i 2-bromo-3-trifluoromethylstyrene; =VCH| 4-fluoro-2-trifluoromethylstyrene;

' 4-fiuoro-3 -trifiuoromethylstyrene; B B 4-fluoro-3-triiluoromethyl-alpha-methylstyrene;

4-chloro-3-trifluoromethylstyrene; 2-chloro-5-trifluoromethylstyrene; 4-fluoro-2-trifluoromethylstyrene;

methyl arylvinyl compounds.

It is another object of the present invention The above compounds are generally prepared by first making the corresponding fluorobromobenzenes, converting these via Grignard reagents to the corresponding primary, secondary and tertiary alcohols (generally utilizing acetaldehyde or acetone), and then dehydrating the alcohols to the desired arylvinyl compounds. "lhe secondary and tertiary alcohols are dehydrated most satisfactorily with an acid catalyst such aspotassium acid sulfate, phosphorus pentoxide, etc., while the primar alcohols are usually most readily dehydrated with strong bases, such as potassium hydroxide, as catalysts. Both the secondary and the tertiary alcohols may also be dehydrated in the vapor phase over dehydration catalysts such as aluminum oxide or silica gel.

Any of the compounds within the above formula may be copolymerized with a monomeric polymerizable vinyl or olefinic compound, preferably one having the general formula where L is selected from hydrogen and alkyl (including methyl) and X is an activating group preferably selected. from C=C phenyl, halogenated phenyl, -COOR (where R is alkyl, preferably methyl or hydrogen) and -CN. Copolymerization with these monomers is facilitated when L is hydrogen in all cases where X is aryl. These materials include methylacrylate, methyl methacrylate, acrylonitrile and other acrylic derivatives such as their amids, styrene, maleic anhydride, dichlorostyrene, butadiene-1,3, chloroprene, isoprene, dimethyl butadiene-1,3, and the like. When the vinyl compound that is mixed with the trifluoromethyl compound contains both an alkyl group such as a methyl group and a phenyl group attached to the same vinyl carbon atom, copolymerization is had only with ditficulty. Compounds such as vinyl chloride, allyl chloride, vinyl acetate and others having less monomer reactivity than has vinylidene chloride also form with the alpha-methyl substituted compounds of the present invention copolymers only with the greatest difliculty. They do copolymerize, however, with the styrene compounds of the present invention that have the alpha carbon atom connected to hydrogen.

The polymerization or copolymerization may be carried out by any of the methods used for the preparation of vinyl polymers. Thus, the polymerization or copolymerization may be accomemulsifying agent, as when the pearl polymer-' ization technique is used, it is found that an adjustment in density of the aqueous liquid is desirable to prevent the pearls from agglomerating into a sticky mass. The adjustment in density is preferably accomplished by dissolving in the aqmous liquid a material such as sodium chloride, calcium chloride and the like that is capable of increasing the density thereof.

The following examples, in which parts are by weight, illustrate the present invention:

, EXAMPLE 1 Preparation of 2-bromo-4-trifluo1omethylstyrene A Grignard reagent was prepared from 70.6 grams of magnesium, 425.6 grams of a distilled mixture of 2,5- and 3,4-dibromo-alpha-trifiuorotoluene having about equal amounts of solid (2,5-dibromo-alpha-trifiuorotoluene) and of liquid (3, l-dibromo-alpha-trlfiuorotoluene), 152.6 grams of ethyl bromide and two liters of absolute ether. This Grignard reagent wasre acted with 144.6 grams of freshly distilled acetaldehyde and the resulting addition product was decomposed with 25% ammonium chloride. After filtering and drying, the ether solution was distilled at 3 mm. pressure. The crude product, having a boiling point of 98108 C., was rectified under vacuum through a ten-inch Fenske column to give 96 grams of 2bromo-alpha-methyl-4- trifluoromethylbenzyl alcohol. Twenty-five parts of this alcohol were incorporated with about 24 parts of crushed potassium hydroxide in a flask and immersed in an oil bath, which was rapidly heated to 180 C., and then gradually to 200 C. for over a. period of one hour. The flask was arranged for vacuum distillation and the pressure was adjusted to mm. This distillate was dried with calcium chloride and the product was then fractionally distilled. Seventeen grams of 2-bromo-4-trifluoromethylstyrene were obtained. This material had a boiling point at 5 mm. pressure of 72-73" C., a density 32 of 1.558 and a refractive index i; of 1.5228 EXAMPLE 2 Preparation of 4-fluoro-3-trifluoromethulsturene 753 grams of 5-bromo-alpha-trifluoro-2-nitrotoluene were prepared from 675 grams of 3-- bromo-alpha-trifluorotoluene by a procedure analogous to that-described by Finger and Reed, Journal of the American Chemical Society, 66, pages 1972-4.(1944). From 653 grams of the 5 bromoalpha trifluoro 2 nitrotoluene' there were obtained 639 grams of 4-bromo-alpha-,

trifiuoro-o-toluidine by a procedure analogous to that used for the reduction of alpha, alpha, alpha- 6-tetrafluoro-2-nitrotoluene, as described in the Finger and Reed article above noted.

266 grams of 4-bromo-2-trifluoromethylbem 'zenediazoniumfluoborate were prepared from 249,,

uct. The distillate was washed several times withv 4 fluoro alpha methyl 3 trifluoromethylbenzyl alcohol were obtained which were rectitied to obtain 22 grams of the pure alcohol. A mixture of 107 grams of this alcohol. grams of phosphorus pentoxide and 1 gram of picric acid was then distilled at 90 to 100 mm. pressure using an oil bath with an initial temperature of 143 C. and a final temperature of 170 C. The distilled product was washed with water, dried with calcium chloride and rectified in the presence of trinitrobenzene to obtain 65 grams of 4-fluoro-3- trifluoromethylstyrene.

The physical constants of the styrene obtained were found to be as follows: B. P. 77-78 C. (40 mm.);

EXAMPLE 3 Preparation of l-fluoro-alpha-methyl-s-trifluoromethulstyrene A Grignard reagent was prepared from 162 grams (0.666 mol) of 5-bmmo-alpha, alpha,

and n 1.4522.

6 about 63 grams of 4-iluom-alpha-methyl-3-trifluoromethylstyrene were obtained.

The physical constants of'the styrene were as follows: B. P. 80-01 C. (40 mm) and a 1.4530.

EXAMPLE 4 Polymerization of fluorinated styrene:

Samples of 2-hromo-4-trifluoromethylstyrene. 4-fluoro-3-trifluoromethylstyrene and 4-fiuoroalpha-methyl-ll-trifluoromethylstyrene containing 0.5% benzoyl peroxide were placed in small stoppered test tubes (1 x 5 cm.) and heated in an oven at 70 C. After three days the styrenes containing no methyl group on the alpha carbon had completely polymerized. The polymers were hard. tough, colorless, crystal-clear materials. The alpha-methylstyrene failed to polymerize even after several weeks at 70 C.

EXAMPLE 5 Copolymerization of fluorinated styrenes Portions of the trifluoromethyl arylvinyl compounds prepared in each of the above Examples 1 to 3 were mixed with vinyl acetate, methyl methacrylate, styrene and maleic anhydride. and about .5%, based on the weight of the monomeric materials, of the free radical-forming catalyst benzoyl peroxide. The polymerization temperature was 70 C. The percentage by weight of comonomer used in each instance was calculated on a molar basis and both this percentage, the polymerization time and the result of the polymerization are shown in the following table.

TABLE Iluorlnared Styrene g g Result 2-bromo-4-triiluorometh- Vinyl Acetats40% Hard translucent polyyistyrene. mer alter 117 hours. 2-bromo-4-triiiuororneth- Methyl Methacrylate 50%.-. Hard, clear, slightly yelylstyrene. low plastic alter 5 ours. 2hromo-4-trifluorometh- Styrene 50% Hard, clear, colorless y yrenc. plastic alter 17 hours. 2-bromo-4-triiluorometh- Maleic Anhydride 25% Hard, clear, slightly yelylstyrene. low polymer alter ours. 4-iluoro-3-triiiuorometh- Vinyl Acetate 40% Hard translucent polytyrene. mer alter 102 hours. 4- uoro-3-triiiuorometh- Methyl Methacrylate Hard, clear, slightly yelylstyrene. {ow plastic alter 46 ours. Miuoro-B -trlfluoromcth' Styrene 50% Hard, clear, colorless tyrene. plastic alter 46 hours. 4- uoro-3-triiiuorometh- Maleic Anhydride 25% Hard, cloudy plastic lstyrene. alter 46 hours. 4- uoro-alphamethyl-3- Vinyl Acetate 50% No polymer alter l trifluoromethylstyrene. month. 4-iluoro-alphsmethyl-3- Methyl Methacrylate Hard, clear, slightly yeltrifluoromethylstyrens. low mplnstic alter 1 mon i-iiuoro-alphamethyl-S- Styrene 60% Clear, hard, colorless trifluoromethylstyrene. lastic after 12 days. 44uoro-alphamethyl-3- Maleic Anhydride50% C ear, slightly yellow triiluoromethyistyrene. brittle polymer alter 102 hours.

alpha, 2-tetrafluorotoluene and 16.3 grams (0.67, EXAMPLE 6 mol) of magnesium in 900 m1. of absolute ether. 0 l men:

one ation o uoroal l st ene with A solution of 41.5 grams (0.715 mol) of acetone g g w About 25 parts of each of the arylvinyl compounds prepared in Examples 1 to 3, inclusive, were mixed with parts of butadiene and emulsifled in a solution consisting of parts of 70 water, 5 parts of soap (sodium stearate) and .4

part of potassium persullate, in the presence of .2 part of lauryl mercaptan. The mixture in each case was held at about 40 C. with constant agitation for about 40 hours. The latexlarmannertothatdescribedinExampleland 76likeproductsobtainedwereooagulatodwithsalt 7 7 and-sulfuric acid, utilizing the same procedure generally used for the industrial preparation of butadlene-styrene copolymers. A rubbery material was obtained in each instance which had the methods described in Examples 4 and 5 to produce both rubbery and resinous products.

The presence of one or more trifluoromethyl groups and one or more nuclear halogen groups gives to the copolymers and polymers produced therewith desirable thermal properties as well as desirable optical properties so that they are useful for the preparation of many commercial articles.

It is also apparent that modifications of the invention may be made without changing the spirit thereof, and it is intended that the invention be limited only by the appended claims.

What we claim is:

l. 4-fluoro-3-trifiuoromethyl alpha methylstyrene.

2. A monofluoro-trifluor0methy1-alpha-methylstyrene having both carbon atoms of the nucleus, that are ortho to the carbon carrying the rinyl group, connected directly to hydrogen.

8 3. A- nuclearly halogenated trifluoromethylaryl-oleflnlc compound having the general for;

mula

I X CFa) in which X is halogen.

GUSTAVE B. BAcnMAN. woman 1. LEWIS.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,469,845 Renall May 10, 1949 2,522,491 Clark Sept. 19, 1950 OTHER REFERENCES Marvel et al.: J. Am. Chem. Soc., 68, pages 736-738 (May 1946).

9giganoll: J. Am. Chem. Soc., pages 1159-64 (July 1 Bachman et al.: J. Am. Chem. Soc., 69, 2022-25 (August 1947). 

3. A NUCLEARLY HALOGENATE TRIFLUOROMETHYL-ARYL-OLEFINICC COMPOUND HAVING THE GENERAL FORMULA 